Apparatus for centering well tools in a well bore



April 30, 1963 J. w. GRAHAM 3,037,552

APPARATUS FOR CENTERING WELL TOOLS IN A WELL BORE Filed 001;. 2, 1961 I INVENTOR.

JOHN W. GRAHAM,

ATTORNEY.

United States Patent 3,087,552 APPARATUS FOR CENTERING WELL TOOLS IN A WELL BORE John W. Graham, Houston, Tex., assignor, by mesne assigumeuts, to Jersey Production Research Company,

Tulsa, Okla, a corporation of Delaware Filed Oct. 2, 1961, Ser. No. 142,086 2 Claims. (Cl. 166-243) This invention relates generally to well tools, and more particularly to apparatus for the recovery of well tools, such as logging sondes, that have become lodged in a borehole or separated from connecting lines to the earths surface.

It is not uncommon that well tools become lost in wells so as to seriously impede drilling or producing operations. Where the well tool is constructed of dn'llable or dissolvable materials, no particular problem exists. However, many tools, particularly logging sondes, are constructed of materials that are neither drillable nor dissolvable. When such tools are lost in a well, it has been necessary either to bypass them by directional drilling and sidetracking operations or to abandon the hole. Manifestly, neither alternative is desirable. Directional drilling and side-tracking operations are extremely time-consuming and expensive. Furthermore, many well .tools are quite expensive, often costing $25,000 or more at the present time. It is desirable, therefore, to incorporate in the well tools apparatus for facilitating the recovery thereof from boreholes.

In accordance with the teachings of the present invention, there is provided at or near the upper end of an elongated well tool a plurality of downwardly extending pivoted arms arranged to pivot so as to push the tool away from the walls of a borehole. The arms preferably are substantially equi-angularly spaced circumferentially around the tool to insure that the tool will be puhsed away from the borehole walls. The arms are connected to an operator arranged to simultaneously pivot the arms upon movement of the operator longitudinally of the lionsing. Acid soluble means operatively connected to the arms and operator assembly restrains the arms against pivotal movement and then permits longitudinal movement of the operator upon dissolution of the acid soluble means. The acid soluble means may be dissolved either by exposure thereof to acid of appropriate concentration housed therewith in a suitable container or by spotting acid in the well at the level of the housing where the acid thus spotted can reach the acid soluble means.

Objects and features of the invention not apparent from the above discussion will become evident upon consideration of the detailed discussion of the description thereof taken in connection with the accompanying drawing, wherein:

FIGS. 1 and 2 are elevational views of an embodiment of the invention, partially in cross section, illustrating two operative positions of the component parts thereof;

FIGS. 3 and 4 are elevational views, partially in cross section, similar to FIGS. 1 and 2, respectively, illustrating another embodiment of the invention; and

FIGS. 5 and 6 are elevational views of the invention positioned in a borehole. FIG. 5 illustrates the position of the apparatus corresponding to the operative position illustrated in FIGS. 1 and 3, and FIG. 6 illustrates the position of the apparatus upon movement of the component parts to the positions illustrated in FIGS. 2 and 4.

With reference now to the embodiment of the invention illustrated in FIGS. 1 and 2, there is shown the upper end of an elongated well tool, such as a logging sonde, comprising housing sections 4, 5, 17, and 29 connected together in the order named by appropriate connections such as screw-threaded connections. The housing section 29 is for the purpose of housing appropriate well measuring, testing, and/ or treating apparatus and the appropriate control apparatus therefor, and may be of the general type illustrated in US. Patent No. 2,983,5 86, Blanchard.

The upper end of housing section 4 includes a conventional fishing head 3' to which a retrieving mechanism, such as illustrated on page 4158 of the 22nd edition of the Composite Catalog of Oil Field Equipment and Services, may be afiixed. A fragment of a multiconductor logging cable 1 is shown extending into housing section 4 through the fishing head 3. It may be assumed that the logging cable -1 has broken so as to cause the well tool to become lost in the borehole. The logging cable '1 extends through the housing sections 4, 5, and 17 into housing section 29 either through a conduit in the housing sections or a groove cut in the exterior of the housing sections (not shown).

Housing section 5 has a number of elongated openings 8 therein through which extend a plurality of downwardly and outwardly extending arms 7 which are hingedly affixed to the housing section 5. A central cavity 13 within the housing section 5 permits longitudinal movement of an operator mechanism including a cross head 9 afiixed to one end or" a connecting rod 11. The cross head 9 has a number of pins 10 therein slidable within slots 12 in the upper end of each of the pivoted arms 7. Upon downward movement of the cross head, the arms will be pivoted outwardly to the position shown in FIG. 2.

The lower housing section 17 defines a piston cylinder for a piston 25 therewithin which is connected to the end of connecting rod 11 opposite the end to which cross head 9 is attached. The connecting rod 11 extends through upper wall 21 of housing 17, which is afiixed to the housing section 5. An O-ring 19 in a cavity within the wall 21 provides a seal around connecting rod 11. An O-ring 27 provides a seal between the piston 25 and the walls of the piston chamber. A port 24 (see FIG. 2) is provided at the upper end of housing section '17 for providing fluid communication between the borehole and the piston chamber. An acid soluble plug 23 (see FIG. 1) normally seals the port. An acid soluble band 15 in a slot 16 in each of the arms 7 holds the arms in the position shown in FIG. 1 during the time that the tool is run into the borehole. The complete function of the band 15 will become apparent below.

.The manner in which the apparatus described above is used is as follows. Let it be assumed that the well tool has been run into the well and that for some reason the logging cable has become separated so that the tool is in the position shown in FIG. 5. With the fishing head 3 positioned very close to the borehole wall 2, it is almost impossible for a retrieving tool or grapple to be secured to the apparatus so as to permit retrieval of the tool from the well. Therefore, a tubing string may be lowered into the well and a small quantity of acid of suitable concentration may be spotted around the upper end of the well tool. The acid will dissolve plug 23 and band 15. has much as the pressure in the chamber 20 is substantially less than borehole pressure, piston 25 will move downwardly in chamber 20. Arms 7 will spring out to contact the borehole wall 2 as shown in FIGS. 2 and 6 so as to more-or-less centrally position fishing head 3 in the borehole. The tubing may then be removed from the well and a retrieving tool or grapple may be lowered into the borehole on a 'wireline and latched to fishing head 3 to permit removal of the well tool from the borehole.

It will be noted that without the restraining band 15 the differential pressure between the borehole and the chamber 20 operating over the area of the connecting rod 11 will cause the piston 25 to move slowly downwardly in the chamber. While this movement may not be sufficient to move the arms 7 outwardly a sufficient distance to impede downward movement of the tool, restraining band positively prevents such piston movement from occurring. Under circumstances where the differential pressure is sufficiently great, it may not be necessary to dissolve plug 23, but only to dissolve band 15. For deep well applications, therefore, plug 23 may be replaced by an acid-insoluble plug.

The apparatus illustrated in FIGS. 3 and 4 utilizes a chamber 31 in the upper end of housing section 5 for an acid of suitable concentration. An acid-soluble rod 33 is affixed to cross head 9 and extends through the chamber 31 and is prevented against downward movement by a nut 32. A spring 39 is connected between wall 41 and cross head 9 to urge cross head 9 downwardly so as to pivot arms 7 outwardly. A filling port for the placing of acid in the chamber 31 is provided which is sealed by an acid-insoluble plug 35. ,The acid may be hydrochloric acid, sulfuric acid, nitric acid, or acetic acid. Alternatively, rod 33 may be of aluminum and the chamber 31 filled with sodium hydroxide solution.

.The concentration of acid in chamber 31 and the thickness of rod 33 are selected so that the rod will not be dissolved until after a time period which is greater than the maximum time required for the well tool to be in the borehole. For example, if the maximum time for use of the well tool in the borehole is two hours, the acid concentration and rod thickness will be such that the rod will not be dissolved for at least four or five hours. Should the well tool be lost in the borehole, the rod 33 will be dissolved to permit downward movement of cross head 9 -by coil spring 39 so that the arms 7 will spring out into the position shown in FIG. 4, thus permitting easy retrieval of the well tool from the borehole in the manner described above.

The invention is not to be restricted to the specific structural details, arrangement of parts, or circuit connection herein set forth, as various modifications thereof may be effected without departing from the spirit and scope of the invention.

The objects and features of the invention having been completely described, what I wish to claim is:

1. Apparatus for urging the upper end of a well tool away from the walls of a borehole including:

a housing for the tool;

a plurality of pivoted arms substantially equi-angularly spaced circumferentially around the housing and pivotally affixed thereto, said arms extending outwardly and downwardly relative to the housing and adapted to pivot in a plane parallel to the longitudinal axis of said housing;

an operator affixed to said pivoted arms to simultaneously pivot said arms outwardly and upwardly from a restrained position thereof upon movement of said operator in a predetermined direction along the longitudinal axis of said housing;

a closed piston cylinder;

a piston in said cylinder reciprocable parallel to the longitudinal axis of said housing;

a piston rod extending through an end wall of said cylinder, connected to said operator for movement thereof;

a port in one end of said cylinder for permitting flow of borehole fluid into said cylinder to exert borehole pressure on one side of said piston to urge said piston and said operator in said predetermined direction along said longitudinal axis of said housing; and

an acid-soluble closure for said port.

2. Apparatus for urging the upper end of a well tool away from the walls of a borehole including:

a housing for the tool;

a plurality of pivoted arms substantially equi-angularly spaced circumferentially around the housing and pivotally affixed thereto, said arms extending outwardly and downwardly relative to the housing and adapted to pivot in a plane parallel to the longitudinal axis of said housing;

an operator affixed to said pivoted arms to simultaneously pivot said arms outwardly and upwardly from a restraining position thereof upon movement of said operator in a predetermined direction along the longitudinal axis of said housing;

a closed piston cylinder;

a piston in said cylinder reciprocable parallel to the longitudinal axis of said housing;

a piston rod extending through an end wall of said cylinder, connected to said operator for movement thereof;

a port in one end of said cylinder for permitting flow of borehole fluid into said cylinder to exert borehole pressure on one side of said piston to urge said piston and said operator in said predetermined direction along said longitudinal axis of said housing;

an acid-soluble closure for said port; and

an acid-soluble band around said arms for holding said arms in a restrained position thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,482,674 Kriegel Sept. 20, 1949 2,708,000 Zandmer May 10, 1955 2,714,423 Hitchings Aug. 2, 1955 2,735,485 Metcalf Feb. 21, 1956 2,781,852 Rumble Feb. 19, 1957 2,981,332 Miller et al. Apr. 25, 1961 

1. APPARATUS FOR URGING THE UPPER END OF A WELL TOOL AWAY FROM THE WALLS OF A BOREHOLE INCLUDING: A HOUSING FOR THE TOOL; A PLURALITY OF PIVOTED ARMS SUBSTANTIALLY EQUI-ANGULARLY SPACED CIRCUMFERENTIALLY AROUND THE HOUSING AND PIVOTALLY AFFIXED THERETO, SAID ARMS EXTENDING OUTWARDLY AND DOWNWARDLY RELATIVE TO THE HOUSING AND ADAPTED TO PIVOT IN A PLANE PARALLEL TO THE LONGITUDINAL AXIS OF SAID HOUSING; AN OPERATOR AFFIXED TO SAID PIVOTED ARMS TO SIMULTANEOUSLY PIVOT SAID ARMS OUTWARDLY AND UPWARDLY FROM A RESTRAINED POSITION THEREOF UPON MOVEMENT OF SAID OPERATOR IN A PREDETERMINED DIRECTION ALONG THE LONGITUDINAL AXIS OF SAID HOUSING; A CLOSED PISTON CYLINDER; A PISTON IN SAID CYLINDER RECIPROCABLE PARALLEL TO THE LONGITUDINAL AXIS OF SAID HOUSING; A PISTON ROD EXTENDING THROUGH AN END WALL OF SAID CYLINDER, CONNECTED TO SAID OPERATOR FOR MOVEMENT THEREOF; A PORT IN ONE END OF SAID CYLINDER FOR PERMITTING FLOW OF BOREHOLE FLUID INTO SAID CYLINDER TO EXERT BOREHOLE PRESSURE ON ONE SIDE OF SAID PISTON TO URGE SAID PISTON AND SAID OPERATOR IN SAID PREDETERMINED DIRECTION ALONG SAID LONGITUDINAL AXIS OF SAID HOUSING; AND AN ACID-SOLUBLE CLOSURE FOR SAID PORT. 